Dieting and weight loss for aesthetic (cosmetic) reasons is practised by individuals throughout the world. Scientists, drug developers and food developers have over the past decade introduced a variety of appetite suppressants and/or weight loss drugs and/or “healthy” food ranges in order to assist dieters in their plight to shed the weight.
Dieting is not restricted to humans, but includes other animals, with diet plans for pets being common.
From an evolutionary perspective animals (including humans) have adapted to gorge food and store energy in case of famine. Unfortunately, however, although this was useful in times when food was scarce, now in times where it is possible to constantly eat this can lead to overweight and, in some cases, obesity.
Obesity has become a major public health problem. Health conditions caused or exacerbated by obesity include hypertension, diabetes mellitus, sleep apnea, obesity-related hypoventilation, back and joint problems, cardiovascular disease, non-alcoholic fatty liver disease and gastroesophageal reflux disease.
The body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters) is the most commonly accepted measurement for overweight and/or obesity. A BMI exceeding 25 is considered overweight, while obesity is defined as a BMI of 30 or more, with a BMI of 35 or more considered as serious comorbidity and a BMI of 40 or more considered morbid obesity.
Obestatin is a peptide hormone that is produced in the cells lining the stomach and small intestine of several mammals including humans; it drastically reduces appetite in mice and is expected to do the same in humans.
Surprisingly, obestatin is encoded by the same gene that also encodes ghrelin, a peptide hormone that increases appetite. Ghrelin and obestatin are both derived from a prohormone produced by the same gene and are divided by post-translational processing. The purpose of this mechanism remains unclear, however it explains earlier findings, namely that removing the ghrelin gene from mice did not significantly reduce their appetite.
Obestatin has been considered for use as a drug against obesity, however it would have to be delivered as a nasal spray or by injection, as the peptide is destroyed by gastric juices.
There are currently few treatments for obesity. Of the two drugs approved for use in the US Roche's Xenical™ (which blocks the digestion of fat) is relatively effective at promoting weight loss, but has some unpleasant side-effects. The other drug approved for use in the US is Abbot Laboratories' Meridia™, which has allegedly been proven to be not particularly effective (Schaffer A. www.slate.com/id/2117332, 26 Apr. 2005).
One experimental drug currently in trials is Rimonabant™ (a cannabinoid receptor antagonist) which allegedly stems cravings in humans, thus reducing obese patients' appetites.
There therefore is a need for an effective tool for reducing weight, preventing weight gain, facilitating weight loss and/or treating obesity.
Among microorganisms, in particular among bacteria, some have a positive influence on the immune system, in particular the lactic acid bacteria and bifidobacteria, and are described as “probiotic” bacteria or strains.
Generally, by probiotic bacterium or strain it is meant a non-pathogenic microorganism which, when ingested live, exercises a beneficial effect on the host's health or physiology. These probiotic strains generally have the ability to survive the passage through the upper part of the digestive tract. They are non-pathogenic, non-toxic and exercise their beneficial effect on health on the one hand via ecological interactions with the resident flora in the digestive tract, and on the other hand via their ability to influence the immune system in a positive manner via the “GALT” (gut-associated lymphoid tissue). Depending on the definition of probiotics, these bacteria, when given in a sufficient number, have the ability to progress live through the intestine, however they do not cross the intestinal barrier and their primary effects are therefore induced in the lumen and/or the wall of the gastrointestinal tract. They then form part of the resident flora during the administration period. This colonization (or transient colonization) allows the probiotic bacteria to exercise a beneficial effect, such as the repression of potentially pathogenic micro-organisms present in the flora and interactions with the immune system of the intestine.
The probiotic strains most commonly used, in particular in dairy products, are principally bacteria and yeasts of the following genera: Lactobacillus spp., Streptococcus spp., Enterococcus spp., Bifidobacterium spp. and Saccharomyces spp.
Among the probiotic effects recorded for these bacteria, there can be mentioned for example the improvement of lactose tolerance, enhancement of immune function, prevention or treatment of gastrointestinal and urogenital infections and reduction of the cancer risk.